Process for a Depth Thermal Treatment in Maize for Producing High Performance Integral Nixtamal and Reactor for Obtaining Necessary Conditions for the Process

ABSTRACT

A process and reactor used for the depth thermal treatment in maize for producing High Performance Integral Nixtamal, a process for treating maize under conditions different from known ones and by which a new product can be manufactured which has been called High Performance Integral Nixtamal.

FIELD OF THE INVENTION

Providing a different technology to cook in a depth way maize, other grains, cereals or legumes, increasing its internal temperature and humidity, in order to obtain a controlled and homogeneous transformation of its components, reducing the loss of pericarp, the loss of process, gas emissions and contaminated wastewater.

BACKGROUND OF THE INVENT/ON

The state of the art used in the tortilla shops for the production of nixtamal involves pouring maize, without prior washing, into an open container and in which excess lime and water is added, in the bottom of the tank is placed a burner, generally butane-based, that is ignited until the water reaches a temperature that can range between 88° C. and 96° C. depending on the height above sea level, the necessary time may range between 60 and 90 minutes, depending on the amount of maize, the capacity and efficiency of the burner. Subsequently it is allowed to stand in the cooking water for a period of 10 to 12 hours, after the time elapsed, it proceeds to washing, and grinding it.

The Nixtamal that is produced in this way loses most maize pericarp, component composed mainly of insoluble vegetable fiber, vitamins, minerals and antioxidants naturally found therein, as its dilution by excess lime, they are throwed away with the wastewater to the drainage. The tortilla/maize performance or rate that is obtained with this nixtamal quality ranges between 130 and 150 kilograms of tortilla per 100 kilograms of maize.

From traditional tortilla shops, family-scale business, 90% about, working within a production capacity range of 300 to 800 kg of tortillas per day, for this is necessary to produce 350 to 900 kilograms of nixtamal daily. In these businesses, and in similar that work using nixtamal flour as raw material, is supported almost the entire supply of tortillas in Mexico.

From nixtamal characteristics depend significantly the results both economic and product quality of the tortilla shops, however, so far it has not been given sufficient importance and it lacks of equipment with new technologies that improve the procedure for cooking maize, as customary to level of the traditional tortilla shop, equipments to help them improve its profitability and product and being compact, simple to install, easily operated and early return on investment.

The way as currently is produced Nixtamal is susceptible of widely improved, observing these opportunities for improvement, is that a new especial apparatus was designed, thereby may be work under process conditions, controlled and different to produce a better nixtamal, a High Performance Integral Nixtamal.

The total of the tortilla shops operating in the country approximately 60% of them use maize as raw material to produce nixtamal, that when milled, it produces necessary dough to make tortilla, the rest uses nixtamalized maize flour, product that is made in large industrial facilities and which, when moisturizing it, produces dough which becomes tortilla.

The Tortilla/Maize transformation ratio with the traditional system depends on the control degree on the operation thereof and is within a range of 130 to 150 kg tortilla per 100 kg maize. The ones that use nixtamalized maize flour operate within a range of 175 to 185 kilograms tortilla per 100 kilograms flour.

When working with a tortilla shop with High Performance Integral Nixtamal such as that produced with the process and special equipment that is sought to be protected with the patent application described here, is obtained a transformation ratio, using maize as raw material of 170 to 180 kilograms Tortilla per 100 kilograms maize.

This new technology applied to maize and other grains satisfactorily resolves current, ancestral problems, in tortilla shops installed in the country and that use maize as raw material, providing improvements such as:

-   significantly reducing the time required for cooking maize and     obtaining Nixtamal; -   to prevent further losing an important part of vegetable fiber,     vitamins, minerals and antioxidants that are part of the grain,     constituting a loss that affects the production cost and discredit     nutritional properties of the tortilla; -   significantly reducing the flow of contaminated wastewater; -   increasing the tortilla/maize ratio, performance, profiting     production productivity and cost, when being able to obtain the same     amount of tortilla with less maize; -   decreasing the production cost by reducing consumption of fuel     required for cooking; -   to help improve the ecological environment by reducing CO₂ emissions     to the atmosphere and the wastewater flow to the drains.

The process further provides other important advantages like: obtaining a saving within a range of 40% to 50% in the fuel consumption necessary for cooking the maize, this advantage integrated to obtain a higher performance in the conversion of maize to tortilla, will benefit the economy of business thousands making them more profitable.

A significant positive consequence by the reduction in fuel consumption is the decreasing in the same proportion, in the flue gas emissions, mainly CO₂, gases which cause greenhouse effect causing a change in weather patterns being observed.

Another important advantage is that tortilla that is obtained with High Performance Integral Nixtamal, processed with this system, has better nutritional properties as it preserves practically, all components contained in the pericarp, like: as dietary or insoluble vegetal fiber, vitamins, minerals and antioxidants, same as in the traditional process are lost in large part since are diluted with cooking water and discarded, literally to the drain, further with this system the tortilla that is obtained is digested and assimilates better by its fiber additional content and higher gelatinization of the maize starches, advantages obtained with the depth cooking process at a higher pressure and temperature than the traditional process.

It is an advantage to increase up to two and a half times the content of dietary or vegetal fiber since the gastrointestinal system should not digest nor assimilate and instead of it does help to cause a sense of satiety decreasing appetite and is achieved a satisfaction with lower intake of food.

These advantages will benefit millions of consumers because the tortilla is the basis of the daily diet in Mexico.

They are reported in national censuses, annual consumptions per capita on the order of 120 kg, this is an average of 328 grams per day which is equivalent to about 12 tortillas.

The results discussed here were obtained in a real way and scale of an regular tortilla shot, since in addition to having designed and manufactured this special system of cooking maize for the production of High Performance Integral Nixtamal and reason for this request, it also was installed a commercial stone mill for milling nixtamal and producing dough and a commercial tortilla machine in order to produce tortillas. In this manner it has a pilot facility capable of producing the new High Performance Integrated Nixtamal and dough, to make 3000 tortillas per hour, of a quality higher than the standard, this facility has been operated daily for several weeks with the results here presented, during this period it has been sold the tortilla produced with the purpose of verifying the acceptance from public.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of the process.

FIG. 2 shows a general arrangement of equipment.

FIG. 3 shows a detailed reactor design.

DETAILED DESCRIPTION OF THE INVENTION

The characteristic details of this novel system to process maize and other grains, cereals or legumes will be given clearly in the following description. The equipments comprising the production system, necessary to provide the necessary conditions of the process, are a basket where maize is deposited to be thermally treated, an electric winch to move or lift the process basket and insert it in the wash tank, in which, with water and agitation are removed insecticide residues, dust and foreign material; also has a fixed structure but swivel where is installed electric winch necessary to move the wash tank basket to reactor cooking tank, where they will be generate the thermal and pressure conditions required by the process and where is achieved the transformation of maize in a High Performance integrated Nixtamal.

FIG. 1 shows a flowchart of the required process for depth cooking of maize and obtaining of a High Performance Integrated Nixtamal and specially designed equipment for this purpose. The process begins by introducing the basket (1) with maize (2), this tank is supplied with water at room temperature, subsequently is stirred maize to remove dust adhered to it, insecticide residues used in grain storage and floating separate foreign matter other than maize. Simultaneously is being recirculating water of the maize wash by pump (7) that sends dirty water to the filter (8) which removes impurities and returns the clean water to the wash tank. The previous washing procedure maize despite being very important it is something that is rarely made.

Once the maize is clean with the assistance of the support structure and the electrical winch, the process basket is removed of the washing tank (2) and with assistance of the rotating structure and the winch the process basket (1) is inserting to the reactor cooking tank (3), hot water is added at 60 degrees Celsius from the solar heater (4) and hydrated lime at a ratio which may range with maize type, between 1 and 3 parts by maize thousand, stirring to homogenize. The combustion chamber (5) is ignited which discharges combustion gases to the reactor (3) and the same to the atmosphere through chimney (6). Once the combustion chamber (5) is ignited, the temperature inside reactor (3) is increased; depending on the maize variety and age, the temperature rises to reach 90 to 100 degrees Celsius, once a temperature is reached at a time which may range from 12 to 15 minutes, the combustion in the chamber (5) is suspended, from this point it initiates a rest time which may range between 20 and 30 minutes, in order to homogenize the internal humidity taken by the grain, time at which is maintained temperature in the reactor cooking tank (3). When the rest time is finished, the combustion chamber (5) is re-ignited and temperature is raised inside reactor to a level which may range between 115 and 120 degrees Celsius and a pressure within a range of 1 to 1.3 kg/cm², thus it achieves a depth or higher penetration cooking in the grain without losing the pericarp; by reaching these process conditions, the combustion in the chamber (5) is suspended and starts an rest period at constant temperature and by a time which may range between 5 and 10 minutes, on finishing this step, it proceeds to reduce pressure inside reactor up to atmospheric pressure level, it proceeds to open lid thereof, and with assistance of the winch and the support rotary structure the process basket (1) is removed and positions inside the washing tank (2) for cooling with water from the purifying equipment, water when passing through the ultraviolet ray lamps and with ozone injection it is purified, lowering bacterial content. In this way a product is obtained with a longer duration, without having to add preservative additives. Once nixtamal temperature is within a range 25 to 35 degrees Celsius, it unloads the process basket (1) and nixtamal is transferred to mill. At this point the process ends for the production of High Performance Integral Nixtamal.

FIG. 2 shows the equipment involved in the process and not shown in the above flowchart:

-   the basket (1) wherein maize is loaded; -   the wash tank (2) wherein the basket (1) is initially introduced; -   the electric winch (9) and rotating support structure (10) are     necessary to transfer the basket to the reactor (3); -   the reactor lid (12) which opens to admit basket (1) within reactor     (3); -   a hinge and clamping system of the lid (14); -   the solar heater (4) supplying hot water to the rector; -   gas burners (15) providing required thermal energy; -   the combustion chamber (5) providing required temperature to the     burners (15) to ensure complete combustion of the gas; -   a chimney (6) that induces secondary air flow and combustion gases     through chamber and reactor (3) and discharge them into the     atmosphere; -   security device (13) against vapor overpressure and temperature     measurement and pressure inside reactor (3); -   bactericidal treatment equipment (11) to purify water used at the     end of the process to cool Nixtamal contained in the basket (1) and     returning to the washing tank (2) for its cooling.

FIG. 3, reactor drawing specially designed to generate required specific conditions of the production process of the High Performance integrated Nixtamal.

Drawing shows the most important parts that integrate the reactor and are following:

-   reaction tank (1), cylindrical metal container designed to operate     at pressure and high temperature; -   upper metal lid (2) which can be rotated and placed vertically with     hinge support (3) for accepting the basket inside the reaction tank     containing the maize to be processed. -   flanges (4) installed in the tank (1) and the lid (2) for clamping     both sides and sealing the inner and preventing heat and steam     leakages during work; -   internal support (5), welded to the tank (1) to support basket; -   metal chimney (6), part of system that will cause by natural     induction an air flow through reactor and combustion chamber (7); -   combustion chamber (7), metal container that provides a high     temperature inside atmosphere in order of 800 degrees Centigrade to     ensure that the fuel is fed to the burners (8) to burn efficiently     without loss into the atmosphere; -   chamber (7) is thermally insulated with the purpose of preventing     heat losses and has a device (9) for controlling the secondary air     flow entering to the system; -   hot air supplied by the chamber (7) is induced by chimney (6) within     the high temperature chamber (10) located at the reactor bottom,     chamber formed by a concentric metal ring (11) welded to the outer     wall of the pressure tank (1) and to the inner wall and outer     cylindrical concentric metal bottom (12), this chamber (10) directs     the ascending heated gas flow to the second chamber (13) through an     annular space (12) comprising between wall of two tanks, space     located and designed with an area for conducting gas flow and     obtaining maximize heat transfer to the interior of pressure tank     (1); -   the reactor comprises three serial additional chambers (13), (14)     and (15) for heat transfer to the interior of tank (1) formed by     directional concentric metal rings (16) (17) and (18) respectively,     welded to the outer wall of the tank (1) and to the interior of the     tank (12). Each chamber mentioned has an annular space (19), (20),     and (21) respectively, spaces located between two tanks, so as to     direct the ascending gas flow between a chamber and the next one,     and until gas outlet to the chimney (6); -   the outer tank is thermally insulated by 3 inch ceramic fiber (22)     which at the same time is protected by a stainless steel metal     cover; -   for facilitating control of process conditions, it has a bimetallic     thermometer (23) and a pressure gauge (24), both located in the lid     (2). -   it has a safety device against overpressure (25) located on the top     lid (2). 

What is claimed is:
 1. A process for depth thermal treating in maize for producing High Performance Integral Nixtamal, wherein starts with the maize washing in the washing tank to remove impurities once maize is clean, it is fed to the reactor tank, water is added at 60° C. from a solar heater and hydrated lime in a ratio of one to three parts per thousand of maize, temperature increases in the reactor tank to reach between 90° C. to 100° C., once temperature is reached in a time of 15 to 20 minutes, heat supply is suspended and it initiates a rest time ranging from 20 to 30 minutes with the purpose to homogenize the internal humidity taken by the grain, upon the end the rest time, it increases again temperature in the reactor tank to a level of 115° C. to 120° C. and a pressure of 1 to 1.3 kg/cm², heat increment is suspending and initiates a rest period at constant temperature and for a time of between 5 and 10 minutes, completing this step it proceeds to reduce the pressure until atmospheric pressure level and maize is removed from the reactor tank to take it to the wash tank to be cooled with purified water, this helping to maintain low bacterial content in the nixtamal, thus a product is obtained with longer duration without having to add preservative additives.
 2. The process according to claim 1, wherein the hydrated lime ratio may range with maize type.
 3. The process according to claim 2, wherein the cooking time may range with maize type.
 4. The process according to claim 3, wherein the pressure and temperature may range with the final quality of Nixtamal to be needed.
 5. The process according to claim 4, wherein the process can be applied to cereals, legumes or other grains.
 6. A specially designed reactor for generating the specified conditions necessary for the process of production of High Performance Integrated Nixtamal, wherein the reactor comprises a cylindrical metal to work under pressure and high temperatures, a upper metal lid that can be rotated and placed vertically with the hinge support to admit the basket inside the reaction tank containing the maize to be processed, flanges installed on the tank and lid to clamp both parts and seal the interior and prevent heat and steam leakages, an inner support welded to tank for supporting the basket, a combustion chamber for providing a high temperature inner atmosphere in the order of 800° C., a chimney to cause an air flow by natural induction ascending through the combustion chamber and the reactor, the hot air supplied by the combustion chamber and which is introduced by the chimney to the interior of the high-temperature chamber inside the reactor, high temperature chamber is formed by a concentric metal ring welded to the outer wall of the pressure tank and the inner wall and to the bottom of the outer concentric metal cylinder, high temperature chamber directs the hot gas flow to a second chamber, serially, heat transfer through an annular space comprised between the wall of the two tanks, located and designed space with an area to direct the ascending gas flow and obtain the maximize heat transfer to the interior of the pressure tank, the reactor has three additional chambers in series for heat transfer to the interior of the reservoir formed by directional concentric metal rings welded to outer and inner was of tanks, each heat transfer chamber having an annular space, space located between the two tanks with the purpose to direct the ascending gas flow between a heat transfer chamber and the next chamber up to gas outlet to the chimney.
 7. The reactor according to claim 6, wherein the combustion chamber is thermally insulated to prevent heat loss.
 8. The reactor according to claim 7, wherein the combustion chamber has a device for controlling the secondary air flow that enters into the system.
 9. The reactor according to claim 8, wherein the outer tank is thermally insulated by ceramic fiber which in turn is protected by a metal cover.
 10. The reactor according to claim 9, wherein it comprises a bimetallic thermometer and a pressure gauge located on the lid to control the process conditions.
 11. The reactor according to claim 10, wherein the reactor has a safety device against overpressure located in the lid.
 12. The reactor according to claim 11, wherein the rector operates by heat transfer through four heat transfer chambers.
 13. The reactor according to claim 12, wherein in the combustion chamber can be used any kind of fuel. 